Plasma brain natriuretic peptide as a prognostic indicator in patients with primary pulmonary hypertension

Prognostic value of high plasma brain natriuretic peptide concentrations in very elderly persons

BACKGROUND

Many elderly persons without heart failure have high plasma concentrations of brain natriuretic peptide (BNP). We investigated the prognostic implications and potential causes of these increased levels.

METHODS

We enrolled 111 persons aged 80 years or older who had no history of hospitalization for cardiac disease, a cardiothoracic ratio < or =55% on chest radiographs, and a serum creatinine level < or =2.0 mg/mL. All subjects had participated in a regular health screening program at our hospital, and were followed for up to 24 months. We studied the correlation of plasma BNP concentration with age, nutritional state, and activities of daily living. Cox proportional hazards models were used to determine the association between BNP levels and clinical outcomes (cardiac hospitalizations, mortality), adjusted for other risk factors.

RESULTS

During follow-up, 8 subjects (7%) were hospitalized with cardiac disorders, and 21 (19%) died. Each 50-pg/mL increase in the plasma BNP concentration was associated with a 1.6-fold increase in the risk of cardiac events (95% confidence interval [CI]: 1.2 to 2.1) and a 1.4-fold increase in total mortality (95% CI: 1.2 to 1.6). Plasma BNP concentration correlated positively with age (r = 0.31, P = 0.001), serum creatinine level (r = 0.23, P = 0.02), and the activities of daily living (r = 0.36, P = 0.0001).

CONCLUSION

In very elderly persons, the plasma BNP concentration may be a biochemical marker of an increased risk of cardiac morbidity and total mortality.

Prostacyclin therapy before pulmonary thromboendarterectomy in patients with chronic thromboembolic pulmonary hypertension

OBJECTIVES

The continuous IV administration of prostacyclin improves pulmonary hemodynamics and prognosis in patients with primary pulmonary hypertension. We investigated whether the administration of prostacyclin therapy to patients before they undergo pulmonary thromboendarterectomy ameliorates pulmonary hypertension in patients with the most severe form of chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

Of the 33 patients with CTEPH who were candidates for pulmonary thromboendarterectomy, 12 patients with severe pulmonary hypertension (pulmonary vascular resistance, > 1,200 dyne. s. cm(-5)) received IV prostacyclin prior to undergoing pulmonary thromboendarterectomy. Right heart catheterization and plasma brain natriuretic peptide (BNP) measurements were repeated at baseline, immediately before surgery, and 1 month after surgery.

RESULTS

During a mean (+/- SEM) follow-up period of 46 +/- 12 days, the IV administration of prostacyclin resulted in a 28% decrease in pulmonary vascular resistance (1,510 +/- 53 to 1,088 +/- 58 dyne. s. cm(-5); p < 0.001) before surgery. Prostacyclin therapy markedly decreased plasma BNP level (547 +/- 112 to 188 +/- 30 pg/mL; p < 0.01), suggesting improvement in right heart failure. Pulmonary thromboendarterectomy caused a further reduction of pulmonary vascular resistance (302 +/- 47 dyne. s. cm(-5)) and plasma BNP levels (60 +/- 11 pg/mL) compared to each preoperative value (p < 0.05). Operative mortality rates were relatively low (8.3%) in patients with the most severe form of CTEPH.

CONCLUSION

The IV administration of prostacyclin caused beneficial hemodynamic effects in patients with severe CTEPH and may serve as pretreatment for patients undergoing pulmonary thromboendarterectomy.

Increased B-type natriuretic peptide (BNP) level is a strong predictor for cardiac dysfunction in intensive care unit patients

Patients admitted to an Intensive Care Unit (ICU) frequently have underlying cardiac dysfunction. Early interventions are sometimes difficult to initiate because of diagnostic uncertainty as to whether cardiac failure is present As B-type natriuretic peptide (BNP) has been shown to be increased in cardiac dysfunction, we sought to demonstrate whether BNP can be used as a screening tool for cardiac dysfunction in patients admitted to ICU. All patients admitted to a combined medical and surgical ICU over a four-week period were included in the study. BNP was measured on the point of admission using a hand-held meter. Clinicians were blinded from the measurement when diagnoses were made as to whether or not the patients had clinically significant cardiac dysfunction. Patients with cardiac dysfunction had a significantly higher level of BNP when compared to the non-cardiac dysfunction group: 516 +/- 385 pg/ml (n = 26) v 67 +/- 89 pg/ml (n = 58) (P < 0.0001) A BNP cut-off value at 144 pg/ml exhibited a 92% sensitivity, 86% specificity and 96% negative predictive value. The sensitivity improved to 96% when the analysis was confined to patients > or = 55 years. At this cut-off value, BNP is a strong predictor of cardiac dysfunction. BNP measurement offers a rapid and affordable way to screen for cardiac dysfunction in patients admitted to ICU. An increased BNP level warrants further cardiac investigations so as to implement early interventions for cardiac decompensation in ICU patients.

The NO − K+ Channel Axis in Pulmonary Arterial Hypertension

The prognosis of patients with pulmonary arterial hypertension (PAH) is poor. Available therapies (Ca(++)-channel blockers, epoprostenol, bosentan) have limited efficacy or are expensive and associated with significant complications. PAH is characterized by vasoconstriction, thrombosis in-situ and vascular remodeling. Endothelial-derived nitric oxide (NO) activity is decreased, promoting vasoconstriction and thrombosis. Voltage-gated K+ channels (Kv) are downregulated, causing depolarization, Ca(++)-overload and PA smooth muscle cell (PASMC) contraction and proliferation. Augmenting the NO and Kv pathways should cause pulmonary vasodilatation and regression of PA remodeling. Several inexpensive oral treatments may be able to enhance the NO axis and/or K+ channel expression/function and selectively decrease pulmonary vascular resistance (PVR). Oral L-Arginine, NOS' substrate, improves NO synthesis and functional capacity in humans with PAH. Most of NO's effects are mediated by cyclic guanosine-monophosphate (c-GMP). cGMP causes vasodilatation by activating K+ channels and lowering cytosolic Ca++. Sildenafil elevates c-GMP levels by inhibiting type-5 phosphodiesterase, thereby opening BK(Ca). channels and relaxing PAs. In PAH, sildenafil (50 mg-po) is as effective and selective a pulmonary vasodilator as inhaled NO. These benefits persist after months of therapy leading to improved functional capacity. 3) Oral Dichloroacetate (DCA), a metabolic modulator, increases expression/function of Kv2.1 channels and decreases remodeling and PVR in rats with chronic-hypoxic pulmonary hypertension, partially via a tyrosine-kinase-dependent mechanism. These drugs appear safe in humans and may be useful PAH therapies, alone or in combination.

Plasma concentrations of N-terminal pro-brain natriuretic peptide in control children from the neonatal to adolescent period and in children with congestive heart failure

OBJECTIVE

To determine plasma levels of N-terminal pro-brain natriuretic peptide (N-BNP) in control children to establish a normal age-dependent range from the neonatal period to adulthood. In addition, plasma concentrations of N-BNP were measured in children with congestive heart failure (CHF) and correlated with ejection fraction and clinical symptoms of heart failure.

METHODS

For establishing a normal age-dependent range of plasma N-BNP, venous blood samples were taken in 133 control patients from the neonatal period to adulthood (10 days-32 years) and in 31 children with CHF. Plasma N-BNP levels were determined by an enzyme immunoassay. In children (1 month-14 years) with CHF, plasma N-BNP levels were correlated to ejection fraction measured by echocardiography and clinical symptoms of heart failure using the Ross Score.

RESULTS

N-BNP levels in control children, adolescents, and adults did not show a significant age-related difference. In control children, the normal range was established between 150 (10th percentile) and 430 fmol/mL (90th percentile). Mean plasma N-BNP in control children was 311 fmol/mL (range: 74-654 fmol/mL). In 31 children with CHF, the plasma N-BNP levels were significantly higher (mean: 846; range: 219-2718) than in control children. N-BNP levels showed a negative correlation with the ejection fraction (r = -0.53) and a positive correlation with the clinical heart failure score (r = 0.74).

CONCLUSIONS

Plasma N-BNP levels reflect the severity of symptoms of heart failure and the impairment of cardiac function in children with CHF. In the future, determination of plasma N-BNP levels may be used as a helpful adjunct to monitor the effect of various treatments for CHF in children.

Significance of a plasma D-dimer test in patients with primary pulmonary hypertension

BACKGROUND

D-dimer, a degradation product of fibrin, has been increasingly used as a marker or prognostic factor in various thrombotic diseases.

OBJECTIVE

To assess the significance of a d-dimer test in patients with primary pulmonary hypertension (PPH).

PATIENTS AND METHODS

Fourteen patients with PPH (12 women and 2 men) aged 25 to 68 years (mean +/- SD age, 50 +/- 14 years) entered the study. Plasma d-dimer was determined by Miniquant assay (Biopool International; Venture, CA) 3 +/- 5 months after the disease onset, and patients were followed up for 1 year. We compared the d-dimer levels to the demographic, clinical, and hemodynamic data of the patients.

RESULTS

D-dimer levels were positively correlated with New York Heart Association classification (r = 0.59, p = 0.01) and pulmonary artery pressure (r = 0.43, p = 0.03) and were negatively correlated with oxygen saturation (r = - 0.45, p = 0.03) and 6-min walk distance (r = - 0.49, p = 0.04). One-year survival was also negatively correlated with d-dimer (point-biserial r = - 0.71, p = 0.004), with a higher d-dimer value associated with poorer survival. No significant correlations were found between d-dimer values and sex, age, diffusing capacity of the lung for carbon monoxide, or cardiac index.

CONCLUSION

D-dimer levels may have a role in the evaluation of patients with PPH. This simple, noninvasive test may be helpful for identifying patients who are at a higher risk for severe disease.

Natriuretic peptides in the diagnosis of heart disease--first amongst equals?

The natriuretic peptides and their role in neurohumoral regulation of the cardiovascular system have become the focus of considerable interest from the scientific and clinical community in recent years. BNP in particular has been shown to be an important diagnostic and prognostic marker of use in a wide range of applications. As measurement techniques develop and are refined, routine evaluation of serum levels of these markers is expected to become more widespread. We have reviewed the biochemistry of the natriuretic peptide family, their role in cardiovascular pathophysiology and the evidence supporting their use in the clinical setting.

Differential regulation of atrial and brain natriuretic peptides and its implications for the management of left ventricular volume overload

BACKGROUND

In this study, we investigated the possibility that the atrial and brain natriuretic peptide expression in left ventricular volume overload (VOL) is transcriptionally regulated. We further evaluated the diagnostic and/or prognostic potential of this expression for the management of patients with this disorder.

DESIGN

We compared the myocardial mRNA expression and plasma levels of the two peptides in VOL patients using donor hearts and in healthy blood donors as controls.

RESULTS

The atrial natriuretic peptide (ANP) mRNA was elevated by 38% (P < 0.03) in the right atrium and by 53% (P < 0.003) in the left atrium, but was unchanged in the ventricular chambers of the patient group (n = 19) compared with controls (n = 8). Plasma ANP concentration was elevated by 62% (P < 0.001) compared with blood donor controls (n = 79). It increased slightly (by 36%) 2 h following surgery, and remained at 64% higher (P < 0.03 vs. presurgery) for the 5 days following surgery. The brain natriuretic peptide (BNP) mRNA was elevated by approximately one-fold in both the left ventricle (P < 0.02) and right atrium (P < 0.05), by 94% (P < 0.02) in the right ventricle and by 89% (P < 0.05) in the left atrium. Its plasma level in the patients was 3.4-fold (P < 0.00003) higher than in control subjects. It increased significantly by 1.2-fold (P < 0.01) 2 h following surgery, but dropped significantly (P < 0.05 vs. 2 h post surgery) to presurgical levels 5 days following surgery.

CONCLUSION

The results show chamber-specific elevation in both atrial and brain natriuretic peptide expression and differences in their circulating levels in VOL, suggesting that BNP is a potential prognostic indicator in the postsurgical management of these patients.

Plasma brain natriuretic peptide as a noninvasive marker for efficacy of pulmonary thromboendarterectomy

BACKGROUND

Plasma brain natriuretic peptide (BNP), a cardiac hormone secreted mainly by the cardiac ventricles, has been shown to increase in proportion to the degree of cardiac overload. However, whether plasma BNP may serve as a marker for the efficacy of pulmonary thromboendarterectomy in patients with chronic thromboembolic pulmonary hypertension remains unknown.

METHODS

Plasma BNP level was measured in 34 patients with chronic thromboembolic pulmonary hypertension before and 1 month after pulmonary thromboendarterectomy. Right heart catheterization was also performed before and 1 month after the operation.

RESULTS

Preoperative plasma BNP level was significantly elevated in patients with chronic thromboembolic pulmonary hypertension compared with control patients (246 +/- 40 vs 13 +/- 2 pg/mL; p < 0.001; n = 34) and was positively correlated with total pulmonary resistance (r = 0.57; p < 0.001). After pulmonary thromboendarterectomy, plasma BNP level in survivors markedly decreased (220 +/- 31 to 54 +/- 9 pg/mL; p < 0.001; n = 32) in association with a reduction of total pulmonary resistance (15.6 +/- 1.0 to 4.5 +/- 0.3 Wood units; p < 0.001). The change in plasma BNP level was closely correlated with that in total pulmonary resistance (r = 0.63; p < 0.001). Importantly, a sustained elevation of plasma BNP (> or = 50 pg/mL) indicated the presence of residual pulmonary hypertension (> or = 5 Wood units) after operation (sensitivity = 73%; specificity = 81%).

CONCLUSIONS

Plasma BNP level was strongly associated with the severity of pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension and thereby may serve as a noninvasive marker for the efficacy of pulmonary thromboendarterectomy.

Oral beraprost sodium improves exercise capacity and ventilatory efficiency in patients with primary or thromboembolic pulmonary hypertension

OBJECTIVE

To investigate the effect of beraprost sodium, an orally active prostacyclin analogue, on exercise capacity and ventilatory efficiency in patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension.

PATIENTS AND DESIGN

Symptom limited cardiopulmonary exercise testing was performed before and 3 (1) months (mean (SEM)) after beraprost treatment in 30 patients with precapillary pulmonary hypertension (14 with primary pulmonary hypertension and 16 with chronic thromboembolic pulmonary hypertension).

RESULTS

Long term treatment with beraprost resulted in significant increases (mean (SEM)) in peak workload (87 (4) W to 97 (5) W, p < 0.001) and peak oxygen consumption (peak VO2, 14.9 (0.7) ml/kg/min to 16.8 (0.7) ml/kg/min, p < 0.001). Beraprost decreased the ventilatory response to carbon dioxide production during exercise (VE-VCO2 slope, 42 (2) to 37 (1), p < 0.001). No significant difference in the responses of these variables to beraprost treatment was observed between patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension.

CONCLUSIONS

Oral administration of beraprost sodium may improve exercise capacity and ventilatory efficiency in patients with both primary and chronic thromboembolic pulmonary hypertension.

BNP and congestive heart failure

Brain natriuretic peptide (BNP), a peptide hormone secreted chiefly by ventricular myocytes, plays a key role in volume homeostasis. The plasma concentration of BNP is raised in various pathological states, especially heart failure. Many studies suggest that measurement of plasma BNP has clinical utility for excluding a diagnosis of heart failure in patients with dyspnea or fluid retention and for providing prognostic information in those with heart failure or other cardiac disease. It may also be of value in identifying patients after myocardial infarction in whom further assessment of cardiac function is likely to be worthwhile. Preliminary evidence suggests that measuring the plasma concentration of BNP may be useful in fine tuning therapy for heart failure. Artificially raising the circulating levels of BNP shows considerable promise as a treatment for heart failure. With simpler assay methods now available, it is likely that many physicians will measure plasma BNP to aid them in the diagnosis, risk stratification, and monitoring of their patients with heart failure or other cardiac dysfunction.

Humoral markers of severity and prognosis of critical illness

Despite the considerable advances made in understanding the pathophysiology of systemic inflammation during critical illness, clinical progress has been elusive as it remains a very deadly condition. Cortisol and thyroid hormone levels can be as predictive of outcome as the commonly used severity parameters (i.e. APACHE). Indeed, levels of endocrine humoral substances such as arachidonic acids, nitric oxide, endothelin, calcitonin precursors, leptin and adenosine correlate with the severity and outcome of critical illness. Furthermore, calcitonin precursors represent a potentially new hormokine paradigm, being transcriptionally activated in all cells in response to infection. The cytokines are immune markers that often correlate with severity and outcome, but their release is transient. In contrast, the so-called acute phase proteins, such as C-reactive protein and serum amyloid A, are highly sensitive to inflammatory activity and can be important markers of severity and outcome. Leukocyte esterase, adhesion molecules, platelet activating factor and activated protein C are additional humoral immune markers; the replacement of the latter has been shown to be a promising therapeutic option. Natriuretic peptides are neurocrine humoral markers that have important cardiovascular implications. The level of macrophage migrating inhibitory factor, released by the pituitary, is elevated in sepsis and counteracts glucocorticoid action. Cellular markers to severe stress include the enhanced expression of protective substances in the form of heat shock proteins. High mobility group-1 is a DNA-binding protein and a late mediator of the inflammatory response. Apoptotic markers such as the soluble fas ligand are also elevated in inflammation. In summary, during critical illness, the endocrine, immune and nervous systems elaborate a multitude of humoral markers, the roles of which merit further scrutiny in order to improve therapeutic outcome.

Cellular pathophysiology and therapy of pulmonary hypertension

The identification of several mutations of the bone morphogenetic protein receptor 2 (BMPR2) gene, a member of the transforming growth factor beta receptor family, gives hope for new insights into the pathophysiology of pulmonary hypertension. Genetic predisposition might dictate the responses of pulmonary artery fibroblasts, smooth muscle cells, and endothelial cells, as well as platelets and leukocytes, or their specific interactions with different extrinsic factors. These cells possess distinct subtypes and interact with each other. Pulmonary hypertension is associated with vasoconstriction, remodeling, and in situ thrombosis of the pulmonary arteries, but the initial events and their relationship to the genetic background are presently unknown. Current therapeutic approaches are based on our knowledge of the physiologic regulation of pulmonary artery tone, pathophysiologic changes, and our clinical experience with different treatment strategies. Beyond diuretics and anticoagulants, prostaglandins are generally accepted therapeutic agents for primary pulmonary hypertension and related diseases, whereas high-dose calcium-channel blockers are reserved for a small subset of patients, those who respond favorably to vasodilators in an acute test. Long-term intravenous prostacyclin infusion has become the most important specific therapy for primary pulmonary hypertension and associated diseases. However, this therapy is hampered by catheter complications and systemic side effects. Alternative application routes of prostacyclin or its stable analogs may avoid these problems. Inhaled application of the prostacyclin analog iloprost results in predominant pulmonary vasodilation with few systemic side effects and may possess clinical efficacy similar to that of intravenous prostacyclin. Inhaled nitric oxide is widely accepted as a screening agent for active responders to vasodilators and has a similar hemodynamic profile as inhaled iloprost, although the percentage of responders is considerably lower. However, there are unsolved toxicologic questions and practical difficulties concerning the safe long-term application of nitric oxide. Combining inhaled vasodilators with phosphodiesterase inhibitors may prolong the duration of the effects and improve the convenience of inhaled therapy for pulmonary hypertension. Therapeutic approaches in the future may aim at the transforming growth factor beta pathway and at the identification of early stages of the disease to prevent further disease progression.

Brain natriuretic peptide blood levels in the differential diagnosis of dyspnea

STUDY OBJECTIVES

In dyspneic patients without left ventricular enlargement, it may be difficult to differentiate between obstructive lung disease and diastolic heart failure. Determination of plasma brain natriuretic peptide (BNP) levels, known to increase with ventricular stretch, may be of clinical relevance in this situation. We compared the discriminant power of BNP blood levels and of echocardiography in patients with either chronic obstructive lung disease or diastolic heart failure.

PATIENTS

Twenty-six New York Heart Association class III dyspneic patients with normal left ventricular systolic function were enrolled: 17 patients with chronic obstructive lung disease and 9 patients with unequivocal diastolic heart failure.

RESULTS

Echocardiographic data were unable to accurately differentiate between the two groups, whereas BNP levels were significantly and markedly higher in patients with diastolic heart failure when compared to those with obstructive lung disease (224 +/- 240 pg/mL vs 14 +/- 12 pg/mL, p < 0.0001).

CONCLUSIONS

These preliminary results warrant a prospective, large-scale evaluation of the value of BNP assay for determining diastolic dysfunction, a common cause of dyspnea in elderly patients, and differentiating it from other diagnoses such as obstructive lung disease.

The impact of cardiac natriuretic peptide determination on the diagnosis and management of heart failure

The long-predicted endocrine function of the heart has been proven by the discovery of atrial natriuretic peptide (atrial natriuretic factor, A-type natriuretic peptide; ANP) 20 years ago. This subsequently led to the description of a whole family of structurally similar but genetically distinct peptides, the natriuretic peptide family, which contributes to cardiovascular homeostasis. These looped peptides promote natriuresis and diuresis, act as vasodilators, and exert antimitogenic effects on cardiovascular tissues. Two members, ANP and brain natriuretic peptide (B-type natriuretic peptide; BNP) are secreted by the heart mainly in response to myocardial stretch induced by volume load. The natriuretic peptides are synthesized as preprohormones. The C-terminal endocrinological active peptides (ANP, BNP) and their N-terminal prohormone fragments are found in plasma. The natriuretic peptide system is activated to its highest degree in ventricular dysfunction. However, natriuretic peptides are increased in all patients with edematous disorders which lead to an increase in atrial tension or central blood volume, such as renal failure or ascitic liver cirrhosis. It could be demonstrated that in chronic heart failure patients and during the subacute phase of myocardial infarction, of all tested neurohormones, the cardiac natriuretic peptides were best markers to identify heart failure and the most powerful predictors of morbidity and mortality. Natriuretic peptides are independent markers for risk assessment. In comparative studies BNP was superior to ANP and its N-terminal prohormone fragments in myocardial infarction as well as in chronic heart failure patients. Less data on N-terminal proBNP (NT-proBNP) is available, but BNP and NT-proBNP appear to be equivalent markers. For primary care physicians natriuretic peptide measurement is useful to decide which patient with suspected heart failure warrants further investigation, particularly when assessment of left ventricular function is not readily available. Natriuretic peptides have an excellent negative predictive value, particularly in high risk patients. An increase in BNP is serious enough to warrant follow-up examinations. For the cardiologists the natriuretic peptides are helpful for guidance of therapy and monitoring disease course in heart failure patients and for risk stratification in heart failure and myocardial infarction.

Short-term oral administration of L-arginine improves hemodynamics and exercise capacity in patients with precapillary pulmonary hypertension

We sought to assess the effects of oral supplementation of L-arginine, the precursor of nitric oxide (NO), on hemodynamics and exercise capacity in patients with pulmonary hypertension. Acute hemodynamic responses to oral L-arginine (0.5 g/10 kg body weight) or placebo were examined in 19 patients with primary or precapillary secondary pulmonary hypertension. Cardiopulmonary exercise tests were performed to measure peak oxygen consumption (peak V O(2)) and the ventilatory response to carbon dioxide production (V E-V CO(2) slope) before and 1 wk after treatment with L-arginine (1.5 g/10 kg body weight/d) or placebo. Oral supplementation of L-arginine significantly increased plasma L-citrulline, which indicated enhancement of NO production. Supplemental L-arginine produced a 9% decrease in mean pulmonary arterial pressure (53 +/- 4 to 48 +/- 4 mm Hg, p < 0.05) and a 16% decrease in pulmonary vascular resistance (14.8 +/- 1.5 to 12.4 +/- 1.4 Wood units, p < 0.05). L-arginine modestly decreased mean systemic arterial pressure (92 +/- 4 to 87 +/- 3 mm Hg, p < 0.05). A 1-wk supplementation of L-arginine resulted in a slight increase in peak V O(2) (831 +/- 88 to 896 +/- 92 ml/min, p < 0.05) and a significant decrease in the V E- V CO(2) slope (43 +/- 4 to 37 +/- 3, p < 0.05) without significant systemic hypotension. Hemodynamics and exercise capacity remained unchanged during placebo administration. These results suggest that oral supplementation of L-arginine may have beneficial effects on hemodynamics and exercise capacity in patients with precapillary pulmonary hypertension.